The invention is based on a spray nozzle for a window or glass washing system as generically defined by the preamble to claim 1.
Known window or glass washing systems for vehicles are as a rule used in conjunction with windshield wipers. For headlights, in some cases it suffices to use them without windshield wipers but with a higher pressure. They are actuated if the moisture from precipitation is insufficient to clean the vehicle window. They include a water tank, one or more spray nozzles, and a pump, which pumps water, mixed with cleaning and antifreeze agents under circumstances, with pressure out of the water tank via water lines to the spray nozzles. As a rule, the spray nozzles are secured to a part of a vehicle body, such as a hood, window frame, or the like.
To prevent the spray nozzles from freezing shut at temperatures below the freezing point, heating elements are integrated with the spray nozzles; they are connected to a power supply via plugs located on the outside. The heating elements entail relatively major production effort and expense for the spray nozzles and greater effort of assembly, for laying the electric lines and for contacting the plugs. However, heaters are also known that are passed through a water supply and are embodied as heating coils in the nozzle body.
Furthermore, it is already known to secure spray nozzles to the wiper blade and thus to distribute the spray fluid directly to the wiping region with a short stream length. Since the spray fluid :is concentrated at a region in the vicinity of the wiper blade and is wiped off again in the briefest possible time by the wiping motion, the view is hindered only briefly by the spray fluid applied. A disadvantage of such systems is that weather factors, especially hail and extreme sunshine, have a severe effect on the flexible parts of this arrangement that are needed to span the articulated regions between the wiper arm and the wiper blade. Furthermore, the spray nozzles and water lines, which are exposed to the relative wind, rapidly freeze closed at temperatures below the freezing point, unless enough antifreeze is mixed with the water. As a rule, the frozen water lines and spray nozzles can be thawed again only with great effort.
Expediently, the spray nozzle has an outward opening check valve, which prevents the water line from emptying when the washing system is not in use for relatively long periods. These check valves for the most part operate on the order of a spring and ball system. It is also known, as the nozzle, to use an elastic diaphragm with sealing lips that point outward. This takes on the function of the nozzle and the check valve, because in the pressureless state the sealing lips close, and they open only beyond a certain pressure. As a result, in the pressureless state, the water line remains filled as far as the through opening. The heat transfer from the heating element to the water is unimpeded, and water residues do not become locally overheated and evaporate. As a result, calcium deposits, which over time could plug the narrow conduits in the spray nozzle, are avoided. Furthermore, the highly volatile antifreeze agents stay in the closed spray nozzle, thus assuring optimal protection against freezing. However, it is difficult to attain a certain and in particular relatively high closing pressure, to achieve adequate tightness over the service life, and to keep the spray stream direction, the impact point, and the spray stream geometry within the desired tolerances.
According to the invention, the hoselike part, with its flow conduit, rests tightly in the pressureless state, with an initial tension, on a mandrel. The initial tension, or prestressing, and thus the opening and closing pressure can be varied, and adapted to the desired conditions, by the oversize of the mandrel compared to the flow conduit, by the elasticity of the hoselike part, or by its wall thickness.
The nozzle element can be provided at an arbitrary point of the window or glass washing system, to prevent washing fluid from flowing in reverse or to prevent emptying of the water lines. However, it can also take on the function of the nozzle at the same time, in that the hoselike part on its end having the mandrel forms a spray hole.
The hoselike part of the nozzle element rests tightly against the mandrel with prestressing, in the pressureless state. Under the influence of a water pressure, the hoselike part of the nozzle element widens, and the washing fluid flows through the flow conduit as it opens to reach the spray hole. Upon shutoff of the pump, the water pressure drops, and an intrinsic tension defined by the geometry and elasticity of the nozzle element closes the flow conduit, so that the mandrel is again tightly surrounded by the hoselike part of the nozzle element.
Because of the initial tension of the hoselike part, in the pressureless state the spray nozzle is sealed off such that in the phases of repose between washing phases, all the components and conduits of the spray nozzle that carry water are closed. As a result, during wiping operation without any washing function, no washing fluid emerges from the spray nozzles, even if they are disposed on wiper arms and if elevated forces of acceleration act on the washing fluid at high wiping frequencies or in the case of stroke-controlled wiper arms. Consequently, less washing fluid is used up. The initial tension of the hoselike part in the state of repose can be designed such that the sealing action is preserved over the service life even if material fatigue occurs.
The direction of the mandrel essentially determines the direction of the spray stream, so that with close tolerances, the impact point of the spray stream on the vehicle window or glass can be predetermined. The geometry of the spray stream is determined largely by the spray hole that forms between the mandrel and the hoselike part when the pressure of the washing fluid exceeds the initial tension. If the mandrel has a circular cross section and if the hoselike part has constant elasticity over its circumference, then an annular gap will form, from which the washing fluid emerges.
To provide that the washing fluid will emerge only at a defined circumferential region of the hoselike part, it is expedient that the hoselike part. is solidly joined over the other region of its circumference to the mandrel, so that in this region no water can escape. Often, it suffices for the hoselike part in this region to have a lesser elasticity and/or a greater wall thickness, so that the gap forms between the mandrel and the hoselike part in the circumferential region having the lesser wall thickness and greater elasticity. For the same flow quantity, a more- compact spray stream will develop under these circumstances.
A further option is. that the hoselike part on at least a portion of its circumference protrudes past the mandrel in the longitudinal direction and is braced on the face end of the mandrel.
The geometry of the spray stream can also be varied by means of the cross section of the mandrel, for instance by providing it with at least one flattened region. This flattened region, which deviates from the circular shape, can be either straight or curved. When a pressure is applied, the hoselike part will initially seek to achieve a circular cross section and will thus form a spray hole toward the flattened region of the mandrel. If there are a plurality of flat faces along the circumference, the spray stream can be distributed over a plurality of circumferential segments. This can be achieved for instance by means of a polygonal cross section of the mandrel. To achieve a concentrated spray stream and at the same time make the mandrel stable, it is expedient for the mandrel to taper toward its end.
In a further feature of the invention, it is proposed that on one nozzle body, a plurality of mandrels are provided, which determine the direction of divergent spray streams and over which the elastic nozzle element is pulled. Thus spray streams in various directions through one spray nozzle can be created; the elasticity of the nozzle element is designed such that it can be installed over the mandrels, which advantageously are solidly connected to the nozzle body. Expediently, the nozzle element has a platelike part, by way of which it is connected to the nozzle body. To that end, the platelike part can be glued or welded to the nozzle body or let into the nozzle body and secured by means of a frame. The frame, which expediently positively engages the inside of the platelike part, reinforces the platelike part so that this part maintains its shape even when pressure is exerted on it. Distributor conduits that connect the hoselike parts to Cone another are advantageously machined into the nozzle body and/or into the platelike part from the parting face between the nozzle body and the platelike part. heating lines can be passed to the inside of the mandrels through the water line and the water conduit. These heating lines are advantageously coextruded into the mandrels during production. If the spray nozzle is secured to a wiper arm, then it is expedient to form a retaining bracket onto the nozzle body.